This application relates to the preparation of symmetric and asymmetric linear and cyclic monomeric carbonates and esters using ester-substituted diaryl carbonates such as bismethyl salicyl carbonate as a reactant.
Carbonates and esters play an important role as intermediate products for numerous syntheses and as products for special fields of use including agricultural chemistry and/or medicinal chemistry, among others. Linear carbonates and cyclic aliphatic carbonates are used in the formulation of flavors and fragrances. Carbonates are also used as extractants, plasticizers, spinning dopes for synthetic fibers, electrolytes, and additives for cleansing agents. Esters are also used in agricultural chemistry and/or medicinal chemistry, and esters also find application as plasticizers, UV absorbers and light stabilizers, anti-microbials, surfactants, food additives, fragrance agents, fixatives, insect repellants, dye carriers.
Monomeric carbonates are commonly synthesized by reactions making use of phosgene gas or a solid phosgene precursor such as triphosgene in a reaction with one or two alcohols or in the case of a cyclic carbonates with diols. The adoption of triphosgene is preferred for safety reasons, even though it costs more and is generally less reactive, requiring longer reactions at higher temperatures. However, triphosgene is only “safe” relative to phosgene itself and it is still classified as a very hazardous material that can generate hazardous decomposition products namely hydrogen chloride, chlorine, phosgene in addition to the carbon monoxide as well as carbon dioxide normally resulting from the extreme thermal degradation of organic compounds. Carbonates can also be made from reaction of a carbon dioxide with an alcohols or diols under pressure and in the presence of catalysts.
Monomeric esters can be synthesized by numerous reactive processes including esterification reactions between an alcohol and an acid and transesterification reactions between two esters. The carbonate and ester forming reactions often require long reactions times and/or high temperatures, and/or catalyst to achieve high conversion to desired product.